On page 46 of these lecture notes, it seems to say that if we have a Feistel cipher, and plaintexts $(L_0, R_0)$ and $(L_0^*, R_0^*)$ with corresponding encryptions, then we can determine the key? But ...

I heard that DES is technically “broken” because of attacks involving large amounts of known plaintext. These attacks are obviously academic and highly complicated, so for some intuition I was hoping ...

I'm currently dealing with multiple blowfish-encrypted files that share the same key. All are encrypted using ECB mode judging from their appearance. I don't know what the key is but I know 64 byte ...

I'm currently interested in the problem of generating random-looking URLs from sequential database IDs, like how they do it in link shorteners. One way to do this is to encrypt the sequential database ...

Are precomputation attacks - such as outlined in RFC 3610 chapter 5 - possible on RSA PKCS#1 v1.5 signature generation? If yes, are such attacks taken into account when calculating the cryptographic ...

The "new" kind of ransomware invade your computer and crypt all your files using the RSA-2048.
Personally, I have been victim of cryptodefense: 40000 files encrypted...
I'm not going to pay anything ...

I'm trying to analyze the strength of a block cipher with CBC mode or with ECB mode on the scenario of an exhaustive search attack with knowledge of pairs of plaintext – ciphertext (known plaintext ...

I have the following question about TLS security:
Assume TLS-PSK protected HTTP with AES256-CBC cipher.
When a TLS connection is established, client sends some encrypted data, where the
plaintext is ...

When I want to encrypt chat messages (in ASCII) before sending, whether it brings some bit of security if I add some extra bytes to the message or shuffle it in some way? I can even try to make data ...

Let's assume that Bob, at some point in time, has created a PGP (key length and other parameters are not relevant at this point). For some reason, he has chosen a very poor passphrase, for instance ...

If I encrypt a file of a known format that has a lengthy header (e.g. an XML Excel file), does that render the encrypted file susceptible to a "known plain text" attack? In other words, if the first ...

I have a (long) text in two versions, encrypted and plaintext. I think it was encrypted using a substitution cipher method (I'm pretty sure, indeed).
I'm not good in this matter, I know little about ...

In asymmetric ciphers we publish the public key for anyone, which means an attacker can encrypt any message they want and compare the ciphertext and plaintext without communicating with the owner of ...

I've been struggling on this problem for a while now : the Hill cipher is well-known to be vulnerable to known-plaintext attack due to its linearity. Given a key matrix $K$ of size $n\times n$, one ...

It seems to be believed that encrypting twice with a block cipher using an independent key each time is not as secure as you might expect because of the "meet in the middle" attack.
This is an attack ...

I know a plaintext - ciphertext couple of length 6 for a hill cipher where its key is a [3x3] matrix.
Based on what I've read and learned, to attack and crack keys of [n x n], if we know a plaintext ...

I have a file, which was encrypted with AES-128 in ECB mode. I know the format of the original file and know that all files in this format have the same headers. So, I have an encrypted block and the ...

I know the plaintext (26 bytes long) and cryptotext of block cipher (suspected to be AES) in ECB mode. I can generate hundreds or thousands of such samples, but the samples are not arbitrary. What are ...